Shamecca Davis hugs her son Isaiah Bow, an eyewitness to the massacre at a screening of the new Batman movie, "The Dark Knight Rises" in Aurora, Colo.

Upon learning of the horrific movie-theater massacre near Denver early Friday, your first rational thoughts might have gone something like this:

What … oh, no. Who is this guy? What could cause him to do such a thing?

Such questions reflect our instinctive need to categorize, to force the killer, whatever twisted fantasies may have rattled in his addled skull, into first a profile and then a political template. Otherwise, his actions make little sense.

Neither good nor bad, this just pegs you as someone who wants to understand our world. To large degree, events are only as significant as the people who make them happen. We ask because we want to know, because we must.

We’ve seen this time after time, often in mass killings that define an era: Oklahoma City, Columbine, 9/11, Virginia Tech, Fort Hood. Weren’t the warning signs there? What did we miss?

What caused these people, these killers, to do such things?

We are so shocked by images of gore and loss — such as the iconic photo of the firefighter carrying the bloody child in Oklahoma City — that our minds crave explanation.

This impulse is obviously not new. In Dallas, we’re well aware of a tragic November day nearly 50 years ago, when a president was shot down on our streets and one man was arrested, then murdered while in police custody.

Horrific and apparently inexplicable, but from Lee Harvey Oswald’s arrest in Oak Cliff to long after his death, much debate has gone into his profile and political template. Communist. Anti-communist. Loner. Conspirator.

The event was so consequential, it must have been more than a single, troubled soul reaching for his moment, however flawed in his thinking. But perhaps it wasn’t more.

We will learn much more about the gunman who opened fire in a midnight screening of The Dark Knight Rises, identified as James Holmes, 24, until recently a doctoral candidate. We will ascribe motive and cause and chastise ourselves for signs that were missed, now so obvious. The more disingenuous among us will blame opponents of long standing, those dark forces beyond his ability to resist.